<!DOCTYPE html>
<html lang="en">

<head>
    <meta charset="UTF-8">
    <meta http-equiv="X-UA-Compatible" content="IE=edge">
    <meta name="viewport" content="width=device-width, initial-scale=1.0">
    <script src="https://cdn.jsdelivr.net/npm/vue@2/dist/vue.js"></script>
    <title>插值姓名</title>
</head>

<body>
    <div id="root">
        姓：<input type="text" v-model="firstname"><br><br>
        名：<input type="text" v-model="lastname"><br><br>
        姓名：<span>{{firstname}}-{{lastname}}</span>
    </div>

    <script>
        const vm = new Vue({
            el: "#root",
            data: {
                firstname: "张",
                lastname: "三"
            }

        })


    </script>

</body>

</html>